Electrochemical biosensors are known in the art and have been used to determine the concentration of various analytes from biological samples, particularly from blood. Various configurations of electrochemical biosensors are described in U.S. Pat. Nos. 5,413,690; 5,762,780; 5,798,031; 5,997,8171; 7,073,246; 7,195,805 and 7,473,398 and U.S. Patent Application Publication No. 2005/0016844, the disclosures of which are each expressly incorporated herein by reference in their entirety.
As the number of patients suffering from diabetes and similar medical conditions increases, self-monitoring of blood glucose where the patient monitors his or her blood glucose level has become common practice. The purpose of monitoring the blood glucose level is to determine the blood glucose concentration level, and then to take the requisite corrective action based on whether the level is too high or too low in order to bring the level back within a normal or acceptable range. Failure to take corrective action can result in serious medical implications. Glucose monitoring is a fact of everyday life for millions of diabetic individuals. Additionally, failure to test blood glucose levels properly and on a regular basis can result in serious diabetes-related complications, including cardiovascular disease, kidney disease, nerve damage and/or blindness.
A number of biosensors utilize electrochemical analysis to determine the blood glucose level by measuring a current that corresponds to an analyte concentration. Such biosensors may utilize a capillary chamber having an electrode substrate providing a working electrode area located in the capillary chamber. The current response of the electrochemical cell is directly proportional to the working electrode area. However, variations in the working electrode area may result from the manufacture and assembly of the components of the biosensor that define the capillary chamber and the position/location of the working electrode. Variations in the working electrode area in the capillary chamber from one biosensor to another are undesirable since such variations introduces imprecision and/or inaccuracy in the measured analyte concentration, which may in turn result in an imprecise and/or inaccurate measurement of the blood glucose level.
Therefore, biosensor arrangements which minimize variations in the working electrode area associated with the manufacture of the biosensor are desirable. Additionally, maintaining a balanced ratio between the counter electrode area and the working electrode area in the capillary chamber is also desirable in order to increase the precision and/or accuracy of the biosensor.